Single track location Shear Wave Elasticity Imaging of the liver with reduced propagation windows

Shear Wave Elasticity Imaging (SWEI) measures the elastic properties of the liver noninvasively, with application to staging liver fibrosis. To make a useful estimate, a shear wave of sufficient amplitude must be generated in the liver. Tracking speckle size determines the distance over which the wave must be tracked, as speckle bias overwhelms estimates made over only a few speckles, but amplitude decays with propagation due to geometric spreading and attenuation. Single-track-location SWEI (STL-SWEI) has shown promise for eliminating speckle bias, and is demonstrated here to yield accurate measurements with reduced propagation windows in an in vivo volunteer study. Transmit focusing for displacement tracking is demonstrated to be important for both MTL-SWEI and STL-SWEI.